My source for this isnt necessarily accurate, however they say the mains freq is accurate in the uk over a 24 hour period from 9 am till 9 am, they speed up and slow down the gensets during the 24 hours and at night time they control the speed to get the right amount of cycles for the last 24 hours, ie your clock might speed up and slow down during the day, but at 9 am it'll be spot on. That could be twaddle I heard it on a well known vintage radio forum. The stability of the mains frequency varies depending where you are, the us however has a large grid system and logic states that they'd have to keep the frequency accurate to maintain compatibility for switching suppliers which happens all the time. A 32.768 xtal osc is a good one to start with, the 32.768 is designed for watches and divides down by 2 to 1 hz and they are stable when loaded with the correct capacitance, next up would be a crystal oven, do a google for that, my later designs are synced to the npl msf time code sgnal on 60kc's, you can get a receiver on ebay for a few quid, similar services are in use around the globe.
On 19 Jan, 00:35, Lucky <dave.lucky.po...@gmail.com> wrote: > From the National Grid (Who supply/transmit our electricity) "System > frequency will therefore vary around the 50 Hz target and National > Grid has statutory obligations to maintain the frequency within +/- > 0.5Hz around this level. However, National Grid normally operates > within more stringent 'operational limits' which are set at +/- 0.2Hz. > " > The figure of 50Hz is derived from the alternators rotational speed of > 3000rpm, 3200rpm/60Hz for the US. Most government institutions from > the Post Office to the Railways used to use mains driven clocks and it > was made statutory that the frequency would always average out at > 50Hz. > Whilst trying to find WHY we chose 3000 and the US 3200 (Which I > didn't find) I did come across some interesting sites one being the > National Grid themselves with a 'live' frequency graph > here:http://www.nationalgrid.com/uk/Electricity/Data/Realtime/Frequency/Fr... > and a snazzy live meter here:http://www.dynamicdemand.co.uk/grid.htm# > > Even better, who says Nixie clocks are not accurate? > See:http://www.leapsecond.com/pages/atomic-nixie/including one of David > Forbes Scopeclocks both "accurate to a few nanoseconds a day"! > > On 18 Jan, 20:00, Dutchgray <dutchg...@gmail.com> wrote: > > > > > > I guess that the additional question would be: How stable is the mains > > > frequency in the UK? > > > Its supposed to be stable and analogue clocks driven from the mains > > were once the norm in public buildings. I would use it as a time base.- > > Hide quoted text - > > - Show quoted text - -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
